EPWS 310 FINAL EXAM, Fall 2010
1. (2 pts each) Define the following:
2. (10 pts) Chose one of the following diseases (Streptomyces scabies on potato or Erwinia caratovora on potato) and answer the questions below about its disease cycle. For 5 extra credit points, answer for both diseases.
a) Where does the pathogen overwinter?
b) How is the pathogen disseminated?
c) What are the symptoms of the disease?
d) How does the pathogen enter the plant?
e) How can the disease be controlled?
3. (10 pts) Draw and label disease progress curves for monocyclic and polycyclic diseases. Name a disease that would be expected to show each type of curve.
4. (12 pts) Using all the components of the disease pyramid, discuss the epidemiology of a specific (1) fungal disease, (2) bacterial disease, (3) viral disease, and (4) nematode disease.
5. (8 pts) Environmental factors influence disease caused by pathogens. Give examples of how temperature (a) high temperature and (b) low temperature influence disease, and how moisture (a) high moisture and (b) low moisture influence disease.
6. (5 pts) Sedentary endoparasitic nematodes can cause severe problems on a wide range of hosts such as corn and turf. How do they interact with the plant? What sorts of symptoms do they cause?
7. (12 pts) Compare the dissemination and overwintering survival of (1) Phytophthora infestans which causes late blight of potato, (2) a canker-causing fungus such as Nectria, (3) crown gall bacteria, (4) Botrytis on strawberries, (5) tobacco mosaic virus, and (6) dwarf mistletoe.
8. (10 pts) Due to your experience in this class, you have been called to look at a grape vineyard in Deming. The leaves on the plants are yellow or necrotic around the margins of the leaves. Describe the steps you will take to diagnose the problem. What type of pathogen would most likely cause the disease? What control measures will you recommend for the next yearŐs crop?
9. (6 pts) Plowing under crop residue can be a useful method for managing disease. Give a disease example when this method will work well and an example when it will not help to control disease.
10. (6 pts) Choosing either Verticillium wilt of chile or stem rust of wheat, explain which factors you would chose in designing a predictive model of disease for eastern New Mexico and why. For 3 pts extra credit, answer both questions.
11. (5 pts) White pine blister rust causes severe problems to the forest trees in New Mexico. White pines are completely susceptible and you donŐt want to pour herbicides over the mountains to kill all the Ribes (alternate host).You have decided to write a grant to develop resistance (transgenic or conventional) in pine to the disease. What pathway, growth factor, or plant part will you try to improve? What types of genes will you modify or add to the plant?